Alkali‐Mediated Miscibility of Gelatin/Polycaprolactone for Electrospinning Homogeneous Composite Nanofibers for Tissue Scaffolding

Electrospun natural‐synthetic composite nanofibers, which possess favorable biological and mechanical properties, have gained widespread attention in tissue engineering. However, the development of biomimetic nanofibers of hybrids remains a huge challenge due to phase separation of the polymer blends. Here, aqueous sodium hydroxide (NaOH) solution is proposed to modulate the miscibility of a representative natural‐synthetic hybrid of gelatin (GT) and polycaprolactone (PCL) for electrospinning homogeneous composite nanofibers. Alkali‐doped GT/PCL solutions and nanofibers examined at macroscopic, microscopic, and internal molecular levels demonstrate appropriate miscibility of GT and PCL after introducing the alkali dopant. Particularly, homogeneous GT/PCL nanofibers with smooth surface and uniform diameter are obtained when aqueous NaOH solution with a concentration of 10 m is used. The fibers become more hydrophilic and possess improved mechanical properties both in dry and wet conditions. Moreover, biocompatibility experiments show that stem cells adhere to and proliferate better on the alkali‐modified nanofibers than the untreated one. This study provides a facile and effective approach to solve the phase separation issue of the synthetic‐natural hybrid GT/PCL and establishes a correlation of compositionally and morphologically homogeneous composite nanofibers with respect to cell responses.     

Surface‐treated and multilayered poly(ε‐caprolactone) nanofiber webs exhibiting enhanced hydrophilicity

To improve the hydrophilic properties of poly(ε‐caprolactone) (PCL) nano/microfiber webs for tissue engineering scaffolds, PCL webs of various structures were fabricated by electrospinning with single or double nozzles connected to an auxiliary electrode. Surface‐modified and layered PCL fiber webs were made by including water‐soluble poly(ethylene oxide) (PEO) in the PCL electrospinning solution (single‐nozzle method) or by electrospinning of alternating PCL and PEO solutions using two nozzles (double‐nozzle method), respectively. When the PEO component within the resulting webs was removed by dissolution with distilled water, the remnant PCL webs exhibited two distinct structures. Those made by the single‐nozzle method consisted of nanofibers with high surface roughness, whereas those made by the double‐nozzle method consisted of stacked layers of PCL nanofibers. Both types of structured PCL web showed improved hydrophilicity characteristics compared with those of nanofiber webs generated from a pure PCL solution using a typical electrospinning process. Cell culturing and scanning electron microscopy showed that the interactions between human dermal fibroblasts and the structured PCL scaffolds were very favorable. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 2038–2045, 2007     

Electrospun poly(aniline‐co‐ethyl 3‐aminobenzoate)/poly(lactic acid) nanofibers and their potential in biomedical applications

Poly(aniline‐co‐ethyl 3‐aminobenzoate) (3EABPANI) copolymer was blended with poly(lactic acid) (PLA) and co‐electrospun into nanofibers to investigate its potential in biomedical applications. The relationship between electrospinning parameters and fiber diameter has been investigated. The mechanical and electrical properties of electrospun 3EABPANI‐PLA nanofibers were also evaluated. To assess cell morphology and biocompatibility, nanofibrous mats of pure PLA and 3EABPANI‐PLA were deposited on glass substrates and the proliferation of COS‐1 fibroblast cells on the nanofibrous polymer surfaces determined. The nanofibrous 3EABPANI‐PLA blends were easily fabricated by electrospinning and gave enhanced mammalian cell growth, antioxidant and antimicrobial capabilities, and electrical conductivity. These results suggest that 3EABPANI‐PLA nanofibrous blends might provide a novel bioactive conductive material for biomedical applications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011.     

Influence of solvents on the formation of ultrathin uniform poly(vinyl pyrrolidone) nanofibers with electrospinning

Although there have been many reports on the preparation and applications of various polymer nanofibers with the electrospinning technique, the understanding of synthetic parameters in electrospinning remains limited. In this article, we investigate experimentally the influence of solvents on the morphology of the poly(vinyl pyrrolidone) (PVP) micro/nanofibers prepared by electrospinning PVP solution in different solvents, including ethanol, dichloromethane (MC) and N,N‐dimethylformamide (DMF). Using 4 wt % PVP solutions, the PVP fibers prepared from MC and DMF solvents had a shape like a bead‐on‐a‐string. In contrast, smooth PVP nanofibers were obtained with ethanol as a solvent although the size distribution of the fibers was somewhat broadened. In an effort to prepare PVP nanofibers with small diameters and narrow size distributions, we developed a strategy of using mixed solvents. The experimental results showed that when the ratio of DMF to ethanol was 50:50 (w/w), regular cylindrical PVP nanofibers with a diameter of 20 nm were successfully prepared. The formation of these thinnest nanofibers could be attributed to the combined effects of ethanol and DMF solvents that optimize the solution viscosity and charge density of the polymer jet. In addition, an interesting helical‐shaped fiber was obtained from 20 wt % PVP solution in a 50:50 (w/w) mixed ethanol/DMF solvent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3721–3726, 2004     

Preparation of hierarchically structured PCL superhydrophobic membrane via alternate electrospinning/electrospraying techniques

Superhydrophobic polycaprolactone (PCL) membranes with hierarchical structure were fabricated via alternate electrospinning/electrospraying techniques. Electrospun PCL/methyl silicone oil (PCL/MSO) nanofibers were employed as substrate. PCL/MSO‐PCL microspheres (PCL/MSO‐PCL_MS) hierarchical membrane was prepared via electrosprayed PCL_MS as an additional layer on the substrate. Field emission scanning electron microscopy images showed the formation of hierarchical PCL/MSO‐PCL_MS membranes. Compared to pure PCL fibers substrate (120 ± 1.3°), the water contact angle (WCA) of MSO‐modified PCL membrane was 142 ± 0.7°. The most interesting observation was that the WCA of PCL_MS without any modification could be achieved to 146 ± 2.8°. On this basis, PCL/MSO‐PCL_MS hierarchical membrane possessed superhydrophobic surface with 150 ± 0.6° of WCA. The excellent surface roughness and air‐pocket capacity of hierarchical membranes would make the membranes more hydrophobic. The maximum oil (n‐hexane) adsorption capacity of PCL/MSO‐PCL_MS membrane was 32.53 g g^?1. Oil–water separation efficiencies of the superhydrophobic membranes were all higher than 99.93% after 10 cycles. The hierarchically structured PCL superhydrophobic membranes indicate the potential applications of environmentally friendly biopolymers as separation membranes. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 421–430     

Synthesis,Morphological Structures,and Material Characterization of Electrospun PLA:PCL/Magnetic Nanoparticle Composites for Drug Delivery

The effects of pure and impure magnetic nanoparticles (MPs) with three different concentrations (0.01, 0.1, and 1 wt %/v) on the morphological structure, crystallinity level, thermal properties and constituent interactions of electrospun poly(lactic acid) (PLA): poly(ε‐caprolactone) (PCL)‐based composites were investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and drug release tests using UV–vis spectrophotometry. Tetracycline hydrochloride (TCH), as a typical therapeutic compound, was loaded into these composite fibrous structures to study their application for drug delivery. The infrared spectra of composite nanofibers confirm the successful embedding of MPs into the fibrous networks. The addition of pure MPs increased the solution viscosity and thus promoted the MP dispersion inside the electrospun composite fiber mats. Impure MPs led to considerably lower average fiber diameters, and could generate unique cell structures that were reported for the first time in this study. The accelerated release of TCH was found by adding pure MPs to PLA:PCL blends. This characteristic was reflected in the parameters of Ritger‐Peppas and Zeng models, which were well fitted to our experimental drug release data. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1607–1617     

The Development of Genipin‐Crosslinked Poly(caprolactone) (PCL)/Gelatin Nanofibers for Tissue Engineering Applications

Composite nanofibers of poly(caprolactone) (PCL) and gelatin crosslinked with genipin are prepared. The contact angles and mechanical properties of crosslinked PCL‐gelatin nanofibers decrease as the gelatin content increases. The proliferation of myoblasts is higher in the crosslinked PCL‐gelatin nanofibers than in the PCL nanofibers, and the formation of myotubes is only observed on the crosslinked PCL‐gelatin nanofibers. The expression level of myogenin, myosin heavy chain, and troponin T genes is increased as the gelatin content is increased. The results suggest that PCL‐gelatin nanofibers crosslinked with genipin can be used as a substrate to modulate proliferation and differentiation of myoblasts, presenting potential applications in muscle tissue engineering.

     

Porous electrospun polycaprolactone fibers: Effect of process parameters

The effect of electrospinning process parameters (solution flow rate, applied voltage, spinning distance) on the size and surface morphology of porous electrospun poly(ε‐caprolactone) was investigated in this study. Response surface methodology was implemented for the design and conduction of electrospinning experiments. The feed solution was a 12.5% w/v poly(ε‐caprolactone) (PCL) solution in a binary solvent mixture of 90%v/v chloroform/dimethyl sulfoxide. Spinning distance of 10–25 cm, applied voltage of 10–25 kV and feed flow rate of 0.5–5 mL/h were the range of limiting values of the independent variables used for the development of a central composite design. Second‐order polynomial equations, correlating electrospinning process parameters to relative pore coverage, and fiber average diameter were developed and validated. An increase in any of the investigated parameters (solution flow rate, applied voltage, spinning distance) resulted in the increase of both, pore formation on electrospun fibers, and produced fiber average diameter. Under the experimental conditions investigated, the relative pore surface coverage was 15.8–31.9% and the average fiber diameter was in the range of 1.6–3.3 μm. Applied voltage was proven to be the parameter with the strongest impact on both, fiber diameter and surface morphology. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1878–1888     

Fabrication and characterization of SiO2/PVDF composite nanofiber‐coated PP nonwoven separators for lithium‐ion batteries

SiO₂/polyvinylidene fluoride (PVDF) composite nanofiber‐coated polypropylene (PP) nonwoven membranes were prepared by electrospinning of SiO₂/PVDF dispersions onto both sides of PP nonwovens. The goal of this study was to combine the good mechanical strength of PP nonwoven with the excellent electrochemical properties of SiO₂/PVDF composite nanofibers to obtain a new high‐performance separator. It was found that the addition of SiO₂ nanoparticles played an important role in improving the overall performance of these nanofiber‐coated nonwoven membranes. Among the membranes with various SiO₂ contents, 15% SiO₂/PVDF composite nanofiber‐coated PP nonwoven membranes provided the highest ionic conductivity of 2.6 × 10^?3 S cm^?1 after being immersed in a liquid electrolyte, 1 mol L^?1 lithium hexafluorophosphate in ethylene carbonate, dimethyl carbonate and diethyl carbonate. Compared with pure PVDF nanofiber‐coated PP nonwoven membranes, SiO₂/PVDF composite fiber‐coated PP nonwoven membranes had greater liquid electrolyte uptake, higher electrochemical oxidation limit, and lower interfacial resistance with lithium. SiO₂/PVDF composite fiber‐coated PP nonwoven membrane separators were assembled into lithium/lithium iron phosphate cells and demonstrated high cell capacities and good cycling performance at room temperature. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1719–1726     

Surfaced-modified TiO2 Nanofibers with Enhanced Photodegradation Under Visible Light

Asynchronized surface modification method based on coaxial electrospinning was developed to fabricate high-efficiency photodegradative nanofiber for water purification. TiO₂ nanoparticles assembled uniformly on the surface of polycaprolactone(PCL) nanofibers to form composite nanofibers through one step process. The maximal content of Ti element was 25.6%(mass fraction) in the PCL/TiO₂ composite nanofibrous membrane, which exhibited hydrophilicity and excellent photodegradation under visible light in water. The Rhodamine B dye degraded 96.17% in 120 min under visible light by the PCL/TiO₂ composite membrane. The adsorption behavior fitted Langmuir model well and indicated chemical related adsorption. This PCL/TiO₂ composite nanofibrous membrane has super degradation properties and displays great application potential to environmental protection.     

The tensile properties of electrospun nylon 6 single nanofibers

In this article, we have aimed to mechanically characterize the nylon 6 single nanofiber and nanofiber mats. We have started by providing a critical review of the developed mechanical characterization testing methods of single nanofiber. It has been found that the tensile test method provides information about the mechanical properties of the nanofiber such as tensile strength, elastic modulus and strain at break. We have carried out a tensile test for nanofiber/composite MWCNTs nanofiber mats to further characterize the effect of the MWCNTs filling fiber architecture. In addition, we have designed and implemented a novel simple laboratory set‐up for performing tensile test of single nanofibers. As a result, we have established the stress–strain curve for single nylon 6 nanofibers allowing us to define the tensile strength, axial tensile modulus and ultimate strain of this nanofiber. The compared values of the tensile strength, axial modulus and ultimate strain for nylon 6 nanofiber with those of conventional nylon 6 microfiber have indicated that some of the nylon 6 nanofiber molecule chains have not been oriented well along the nanofiber axis during electrospinning and through the alignment mechanism. Finally, we have explained how we can improve the mechanical properties of nylon 6 nanofibers and discussed how to overcome the tensile testing challenges of single nanofibers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1719–1731, 2010     

Fluorescent PMMA/MEH‐PPV electrospun nanofibers: Investigation of morphology,solvent, and surfactant effect

Electrospinning is a powerful technique to produce nanofibers of tunable diameter and morphology for medicine and biotechnological applications. By doping electrospun nanofibers with inorganic and organic compounds, new functionalities can be provided for technological applications. Herein, we report a study on the morphology and optical properties of electrospun nanofibers based on the conjugated polymer poly[2‐methoxy‐5‐(2‐ethylhexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) and poly(methylmethacrylate) (PMMA). Initially, we investigate the influence of the solvent, surfactant, and the polymer concentration on electrospinning of PMMA. After determining the best conditions, 0.1% MEH‐PPV was added to obtain fluorescent nanofibers. The optical characterizations display the successful impregnation of MEH‐PPV into the PMMA fibers without phase separation and the preservation of fluorescent property after fiber electrospinning. The obtained results show the ability of the electrospinning approach to obtain fluorescent PMMA/MEH‐PPV nanofibers with potential for optical devices applications. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2014 , 52, 1388–1394     

Electrospinning of carboxymethyl starch/poly(L‐lactide acid) composite nanofiber

Carboxymethyl starch (CMS) is a natural polymer derived from sago starch that is obtained from sago palm (Metroxylon spp.). Herein, CMS was used as a polysaccharide source in preparations of composite nanofibers with poly(L‐lactide acid) (PLLA). The incorporation of CMS with PLLA in nanofiber form has great potential to be used in biomedical applications. The composite PLLA/CMS nanofibers were fabricated by electrospinning technique at various ratios of CMS, which were 5, 10, 15, and 20% vol/vol. The composite nanofibers were characterized according to their physical morphology, chemical interaction, wettability, water uptake, and thermal and mechanical behaviors. The result showed that uniform and bead‐free nanofibers were produced at the low ratio of CMS while fractal and discontinuing fiber was observed at a high ratio of CMS. A better mechanical strength was obtained at low CMS ratio as compared with higher one. Fourier transform infrared results showed that there was an interaction between CMS and PLLA after electrospinning. The surface hydrophilicity and water uptake increased with increasing ratio of CMS. The results from the differential scanning calorimeter analysis showed the decrease of the glass transition (T_g) and cold crystallization temperature (T_cc) of the nanofiber after addition of CMS in PLLA.     

Electrospinning preparation and mechanical properties of PVA/HNTs composite nanofibers

In this paper, the PVA/HNTs composite nanofibers with well‐enhanced mechanical properties were successfully prepared by electrospinning technique. The structure and properties of the composite nanofibers were characterized by TEM, XRD, FT‐IR, and DSC. The results indicated that the highly oriented and dispersed HNTs wrapped in polymer matrix were achieved by inducing function during electrospinning processing. The mechanical properties of the PVA/HNTs composite nanofibers depended on HNTs content were investigated, which showed 72.4% increase in tensile strength at optimal filling content. Copyright © 2016 John Wiley & Sons, Ltd.     

Synthesis and mechanical properties of para‐aramid nanofibers

Scalable, bottom‐up chemical synthesis and electrospinning of novel Cl‐substituted poly(para‐phenylene terephthalamide) (PPTA) nanofibers are herein reported. To achieve Cl‐PPTA nanofibers, the chemical reaction between the monomers was precisely controlled, and dissolution of the polymer into solvent was tailored to enable anisotropic solution formation and sufficient entanglement molecular weight. Electrospinning processing parameters were studied to understand their effects on fiber formation and mat morphology and then optimized to yield consistently high quality fibers. Importantly, the control of relative humidity during the fiber formation process was found to be critical, likely because water promotes hydrogen bond formation between the PPTA chains. The fiber and mat morphologies resulting from different combinations of chemistry and spinning conditions were observed using scanning electron microscopy, and observations were used as inputs to the optimization process. Tensile properties of single Cl‐PPTA nanofibers were characterized for the first time using a nanomanipulator mounted inside a scanning electron microscope (SEM), and fiber moduli measuring up to 70 GPa, and strengths exceeding 1 GPa were achieved. Given the excellent mechanical properties measured for the nanofibers, this chemical synthesis procedure and electrospinning protocol appear to be a promising route for producing a new class of nanofibers with ultrahigh strength and stiffness. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2019 , 57, 563–573     

Recent progress in electrospun nanofibers: Reinforcement effect and mechanical performance

Composite materials are becoming increasingly important as structural materials for aeronautical and space engineering, naval, automotive, and civil engineering, sporting goods, and other consumer products. Fiber‐based reinforcement represents one of the most effective manufacturing strategies for enhancing the mechanical strength and other properties of composite materials. Electrospinning has gained widespread interest in the last two decades because of its ability to fabricate continuous ultrafine nanofibers with unique characteristics. The impact of electrospinning on fiber synthesis and processing, characterization, and applications in drug delivery, nanofiltration, tissue scaffolding, and electronics has been extensively studied in the past. In this article, the authors have focused on a comprehensive review of the mechanical performance and properties of electrospun nanofibers as potential reinforcements as well as their advanced nanocomposites. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1171–1212     

UV‐triggered CO2‐responsive behavior of nanofibers and their controlled drug release properties

A novel nanofibrous mat featuring an ultraviolet (UV)‐induced CO₂‐responsive behavior was fabricated via electrospinning and used as a controlled drug release system. First, a random copolymer for electrospinning, poly(N,N‐diethylaminoethyl acrylamide‐co‐N‐benzylacrylamide‐co‐N,N‐dimethyl‐N‐(2‐nitrobenzyl)‐ethaneamine acrylamide‐co‐4‐acryloyloxy benzophenone) [P(DEEA‐co‐BA‐co‐DMNOBA‐co‐ABP)], was prepared based on pentafluorophenyl esters via an “active ester‐amine” chemistry reaction. Subsequently, doxorubicin hydrochloride (DOX)‐loaded P(DEEA‐co‐BA‐co‐DMNOBA‐co‐ABP) nanofibers were fabricated, yielding a new drug‐loaded nanofibrous mat as a potential wound dressing. These DOX‐loaded nanofibers can respond to UV irradiation and CO₂ stimulation. Interestingly, without UV irradiation, the fabricated nanofibers cannot exhibit any responsiveness. Therefore, the majority of the DOX was steadily stored in the nanofibers, even in the presence of CO₂. However, upon UV irradiation, the CO₂‐responsive behavior of the nanofibers was activated and the prepared nanofibers swelled slightly, resulting in the release of around 42% DOX from the nanofibers. Upon further purging with CO₂, the release amount of DOX from the nanofibers could reach up to approximately 85%, followed by the morphological transition from a nanofibrous mat to a porous hydrogel film. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1580–1586     

Preparation and characterization of composite nanofibers of polycaprolactone and nanohydroxyapatite for osteogenic differentiation of mesenchymal stem cells

Nanocomposites of nanohydroxyapatite (nHAP) dispersed in poly(?-caprolactone) (PCL) were prepared by electrospinning (ES) to obtain PCL/nHAP nanofibers. Nanofibers with similar diameters (340 ± 30 nm) but different nHAP concentrations (0-50%) were fabricated and studied for growth and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs). The nanofibrous membranes were subjected to detailed analysis for its physicochemical properties by scanning electron microscopy (SEM), thermogravimetric analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, and mechanical tensile testing. nHAP particles (~30 nm diameter) embedded in nanofibers increased the nanofibrous membrane's ultimate stress and the elastic modulus, while decreased the strain at failure. When cultured under an osteogenic stimulation condition on nanofibers, MSCs showed normal phenotypic cell morphology, and time-dependent mineralization and osteogenic differentiation from SEM observations and alkaline phosphatase activity assays. The nanofibers could support the growth of mesenchymal stem cells without compromising their osteogenic differentiation capability up to 21 days and the enhancement of cell differentiation by nHAP is positively correlated with its concentration in the nanofibers. Energy dispersive X-ray analysis of Ca and P elements indicated mineral deposits on the cell surface. The mineralization extent was significantly raised in nanofibers with 50% nHAP where a Ca/P ratio similar to that of bone was found. The present study indicated that electrospun composite PCL/nHAP nanofibrous membranes are suitable for mineralization of MSCs intended for bone tissue engineering.     

Enhanced morphological heterogeneity of PCL in the presence of PVC with isothermal supercritical CO2 treatment

This report presents a continuing study of the morphological changes of polycaprolactone (PCL) with isothermal supercritical CO₂ treatments at 304 atm and 35 °C in the presence of poly(vinyl chloride) (PVC). DSC and small‐angle X‐ray scattering (SAXS) data find that the CO₂‐assisted melting of PCL at 304 atm and 35 °C recrystallized in the presence of PVC during depressurization of CO₂ can result in a decreased thickness of crystal lamellar layers. Heterogeneity, with a size (21.7 nm for pure PCL) larger than the crystal layer thickness (8.2 nm for pure PCL) and the amorphous layer thickness (4.4 nm for pure PCL), is formed after the supercritical CO₂ treatment. The size of this heterogeneity is found to enhance from 21.7 nm for pure PCL to 29.8 and 34.9 nm for the PCL samples containing 10 and 25 wt % PVC, respectively. These big heterogeneities in the PCL/PVC blends formed during CO₂ depressurization might arise from the segregated PVC‐rich amorphous domains that are located between bundles of the lamellar stacks, possibly as a result of the molecular dragging on PCL during depressurization of the PCL‐interacted CO₂. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 85–93, 2006     

Electrospinning of polystyrene/poly(2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylene vinylene) blends

Ultrafine polystyrene (PS)/poly(2‐methoxy‐5‐(2′‐ethylhexyloxy)‐1,4‐phenylene vinylene) (MEH‐PPV) fibers were successfully prepared by electrospinning of PS/MEH‐PPV solutions in chloroform, 1,2‐dichloroethane, and tetrahydrofuran (THF). Three concentrations of the solutions were prepared: 8.5, 16, and 23.5% (w/v), with the compositional weight ratios between PS and MEH‐PPV being 7.5:1, 15:1, and 22.5:1, respectively. Smooth fibers only observed from 23.5% (w/v) PS/MEH‐PPV solution in chloroform. Improvement in the electrospinnability of 8.5% (w/v) PS/MEH‐PPV solution in chloroform was achieved by addition of an organic salt, pyridinium formate (PF), or by addition of a minor solvent with a high dielectric constant value. The average diameters of the as‐spun PS/MEH‐PPV fibers were between 0.30 and 5.11 μm. Last, photoluminescence of 8.5% (w/v) solutions of PS/MEH‐PPV in a mixed solvent system of chloroform and 1,2‐dichloroethane of various volumetric compositions and the resulting as‐spun fibers was investigated and compared. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1881–1891, 2005